Main cap clearence question - NJFBOA - Home of New Jersey's Camaros and Firebirds

Blacdout96 · 06-21-2009, 11:08 PM

So I'm putting back together my 3.8, and the main cap oil clearance is allowable between .0008 -.0022 . I plasti-guaged, and came to .001 . I talked to the guys on FullthrottleV6. com, and they said im within spec, but on the tight side. So now they got me worried over there ( why I don't know) but I'm afraid that being on the tight side may not be good. I have an oil pump kit that will allow me to boost my pressure form 55psi @1850rpm, to 80-85 psi, so im not too afraid of oil starvation to the bearings.

When I took it to my shop the guy said that my main and crank was within factory spec, so nothing needed to be changed, so its not like the crank got welded and grounded back down.

SO guys, should I worry and get a larger set of bearings, or keep on with the build? Not like I would race it everyday, mainly would be for driving around, but maybe from time to time Id like to take a trip to a small road course and run it around.

camaroAL · 06-21-2009, 11:32 PM

if ur within spec ur fine, just keep in mind, thinner oil with tighter clearance.

DevilDougWS6 · 06-22-2009, 09:23 PM

what he said ^ . numbers are numbers, and if you are within spec then you are good to go. in fact you are pretty close to center spec there so i wouldnt worry at all. but definitely run a lighter viscosity oil.

also be sure to run through your break in period properly. and change the oil after the break in period.

69BirdX · 06-22-2009, 09:25 PM

I wouldnt worry about it. As stated your in spec. Rather be closer to tighter then lose

Blacdout96 · 06-23-2009, 09:45 AM

Whew, good, yeah I just didnt want to go through the hassel of buying another set of mains since these now have plastiguage on them and cant be returned.

Blacdout96 · 06-24-2009, 04:41 PM

So I finished checking the rest of my mains today and heres the numbers I got :

Main 1: .001
Main 2: .002
Main 3: .002
Main 4: .003

What the hell, they aren't consistent, is that okay? or is something wrong there?

DevilDougWS6 · 06-24-2009, 08:31 PM

the only one id be worried about is the .003 thats pretty loose, was the crank polished at all? i know he said it was in spec but he may have been wrong. you may want to recheck yourself as well, make sure you measured it properly.

Blacdout96 · 06-24-2009, 11:16 PM

Yeah, I'll borrow the Micrometer at work tomorrow, see whats going on. the .002's I didnt care about, but to go from .001 to .003 from end to end is crazy.

Blacdout96 · 06-25-2009, 10:12 PM

So I used a micrometer to measure the diameter of my crank....and it's within spec. The diameter can be between 2.4988-2.4998. All the diameters are 2.4998......

Blacdout96 · 06-29-2009, 09:03 AM

So I said the screw it line, and decided to do the alternative route....loctite the studs in. ARP says it's ok to do that, so I installedthem with loctite, rechecked all the numbers, and came out to .002 all across the mains, so now that thats over with, next move is the connecting rods and pistons (.030 over) and screw my timeline that I give, things are popping up left and right that are retarding my abilitiesto get this thing done. Hopefully next summer I can cruise in it.